Stations for measuring the range and angle of a measurement point are known in the prior art. When carrying out a survey using this type of surveying apparatus, several methods are employed. In one such method, a surveying apparatus is directly connected to a post-processing personal computer via a communications cable and transfers data regarding a survey to the post-processing personal computer via a communications cable. In another method, survey data obtained by the surveying apparatus is stored in a memory card or an electronic notebook (or data collector) and transferred to a post-processing personal computer via a communications cable.
However, where any one of these methods is employed, unless an operator takes a surveying apparatus, a memory card, and an electronic notebook and moves back and forth between a site and an office in which a post-processing personal computer is provided, it is impossible to obtain the survey data and coordinate data necessary for surveying work.
Therefore, as described in, for example, Japanese Unexamined Patent Publication No. Hei-8-285600, a method for converting survey values obtained by a survey to image data and transmitting the converted image data to a facsimile device via a telephone network has been proposed as that for collecting data without reciprocating hardware, which is provided as a data recording medium, between a site and an office.
According to the surveying apparatus, it is possible to transmit data regarding the survey values from a site to a facsimile apparatus that is remote therefrom, via a telephone network. However, since the communications direction of the data is limited to one way, it is not possible to transmit data from the office side, where a facsimile is installed, to a work site.
Accordingly, as described in, for example, Japanese Unexamined Patent Publication No. Hei-10-267656, such an apparatus that is able to carry out bi-directional data communications has been proposed, by which bi-directional data communications are made available between a centralized processing device acting as the master station and a plurality of surveying apparatuses acting as client stations.
In the above-described prior arts, although it is possible to carry out bi-directional data communications between a centralized processing device and a plurality of surveying apparatuses, it is not possible to carry out bi-directional data communications between the surveying apparatuses. That is, in the above-described prior arts, although bi-directional data communications can be carried out between a master station and client stations, no bi-directional data communications can be executed between the client stations, wherein the range of utilization thereof is limited.